Reusing sounds within your movie is an effective way to reduce file size. Static sounds can have a variety of effects applied to them, making them sound different from the original. Specifically, cue points can be used to separate portions of a sound, fade them in or out, or mute them.
To apply an effect to a static sound, select the frame that it is attached to and open the Sound panel. Either assign a preset effect from the Effect drop-down or click the Edit button for a custom effect.
Clicking Edit opens the Edit Envelope dialog box that displays the waveform of the sound and any cue points. By default, there are only two points: one for the beginning and one for end. Moving these points horizontally changes the length of the sound for the frame it is attached to. Vertical changes affect volume.
To add cue points, click anywhere on the waveform. With sufficient alteration, one sound can be made into another.